A study of the passive rebound behavior of bipedal robots with stiff and different types of elastic actuation

One of the most important capabilities of bipedal robots for energy-efficient and dynamic locomotion are shock tolerance and energy storage and release. In this paper, we study three robot models with different leg actuation designs by means of highly detailed multibody system dynamics simulation. For this purpose, we first elaborate on the term of energy-efficient and dynamic two-legged hopping and present a performance index. Subsequently we conduct the same experimental setup for passive rebound and soft landing for all models. Among others it is observed that (1) the envisioned dynamic and energy-efficient locomotion cannot be achieved through stiff actuation, (2) the energy restitution can be maximized without sacrificing the dynamic mobility and (3) such passive rebound experiments are well suited to determining the optimal leg actuation design.